GSM is an acronym for Global System for Mobile communication, and actually still is the most commonly & globally used cellular technology, also considered to be a 2G (second generation) technology.
GPRS is layered on top of GSM, and EDGE is an extended or enhanced form of GPRS, both are essentially GSM technologies.
GPRS is layered on top of GSM, and EDGE is an extended or enhanced form of GPRS, both are essentially GSM technologies.